The invention relates to a semiconductor device with a semiconductor body comprising a CMOS image sensor with an active region having viewed in projection first sides and second sides perpendicular to the first sides said active region comprising a matrix of active pixels arranged in rows and columns, each pixel having a photosensitive region, the device further comprising a plurality of circuit elements for operating the pixel in the image forming process, the plurality of circuit elements comprising a first set of circuit elements for read-out of the columns and a second set of circuit elements for controlling the rows. It is to be noted that in this application C-MOS image sensor means that the sensor is based on CMOS (=Complimentary Metal Oxide Semiconductor) technology or on NMOS technology or on PMOS technology. In CMOS technology both NMOS and PMOS technology is used. It is further noted that the photosensitive region normally contains an in-pixel amplifier circuit. Circuit elements for read-out of the columns comprise analog circuit elements for a bias, sample and hold function and digital circuit elements for an addressing function while circuit element for controlling the rows comprise digital circuit elements for a reset function and an addressing function. The circuit elements for read-out of the columns are also referred to as the horizontal read-out (circuitry) while the circuit elements for controlling the rows are also referred to as vertical driver (circuitry).
Such sensors have been in use for imaging transmission patterns from ionizing radiation, that without limitation are used in medical diagnostics. An image sensor to be used for X-ray imaging by a dentist forms an example.
Prior art, in particular PCT Patent Application WO 2007/003495 to ATMEL GRENOBLE that has been published on Jan. 11, 2007 uses CMOS image sensor having an octagonal, more precisely a chamfered rectangular semiconductor body. This is the traditional shape used for X-ray photography by a dentist and results in the largest ratio of image area versus final product outline. A plurality of circuit elements, in particular transistors, is present outside the active region, i.e. outside the matrix of rows and columns of active pixels comprising a photosensitive region. These circuit elements comprise the circuitry that performs among others the line/row selecting/addressing as well as the column selecting/addressing and these are often referred to as vertical driver and read-out circuitry respectively. In the chamfered prior art it is proposed to design all column circuitry below the middle section of the active region (along the short side of the pixel array), i.e. the lower part of the device between the two chamfered regions, in order to release space below the active region to position there the vertical driver circuitry or part thereof, these thus being positioned below the active region in the chamfered parts of the device. A disadvantage of this implementation is related to the layout asymmetry of the column read-out circuit for the different columns of the pixel array. This asymmetry may lead to visible effects in the image that might be difficult to correct by image data post-processing. Besides that the relative long wires connected with the column read-out lines of the columns underneath the chamfered edges are more prone to EMI (=Electro Magnetic Interference) issues that might introduce extra uncorrectable noise in the image.
The present inventors have recognized that these disadvantages can be overcome in a manner that implies additional advantages.